Oxidative process for the preparation of copper quinolinate

Abstract

A process for the preparation of copper quinolinate in which quinoline is oxidized by hydrogen peroxide in sulfuric acid in the presence of copper sulfate wherein the reaction is carried out at a pressure of less than 400 mm Hg. The reduced pressure enables the reaction to be performed at higher temperatures and with greater control; also the reaction time is shortened and the yield improved. Copper quinolinate is used to prepare quinolinic acid which is the starting material for some chromogenic materials used in the pressure-sensitive record material field.

We claim: 
     
       1. A process for the preparation of copper quinolinate by oxidizing quinoline with hydrogen peroxide in a mixture of water and sulfuric acid in the presence of copper sulfate at a temperature of 55°-75° C. and isolating copper quinolinate from the reaction media, wherein the molar ratio of sulfuric acid to quinoline is greater than 1 to 1, the molar ratio of hydrogen peroxide to quinoline is 10.8 to 1 or greater, the concentration of sulfuric acid is from about 10 to about 30% in said mixture, the oxidation reaction is carried out under a pressure of less than 400 mm Hg and said process is performed by adding copper oxide, quinoline and hydrogen peroxide to the reaction media left after isolation of copper quinolinate prepared according to a previous run of the process. 
     
     
       2. A process according to claim 1, wherein the temperature of the oxidation reaction is from 70°-75° C. 
     
     
       3. A process according to claim 1 or 2, wherein the amount of copper sulfate present in the media is supplemented by an amount equivalent to the amount of copper quinolinate prepared in the previous run and the concentration of sulfuric acid present in the media is adjusted to within the range of 10 to 30%.